Mandrel bar



Patented Dec. l2, 1.939

UNITED STATES;

APATENT oFFicE to National Tube Com New Jersey muy, a corporation oi' Application February 11, 1937, sei-1n No. 125,323

3 claims. .(ol. '1s-10s) 'My invention relates to mandrel bars and more particularly to those which are used in the manufacture of pipes and tubes, although not limited thereto. Mandrel bars for pipe or tube mills have a dual purpose. 'I'hey provide means for positioning the mandrel plug, which in conjunction L,with the metal working rolls provides the processing y "pass of the mill and also performs the function of guiding and supporting the work-piece as it leaves the pasa Consequently, the mandrel bar must be somewhat longer than the workpiece being processed and, in order to prevent binding of the work-piece, have an overall diameter at least slightly less than the inside diameter of the work-piece. Since the work-piece is processed 'at high temperatures it is necessary to cool the mandrel bar in order to keep it from becoming too highly heated, and also to prevent 2 0 expansion thereof from moving the mandrel plug too close to the metal working rolls of the mill.

'I'he customary practice has heretofore been either to entirely illl the hollow mandrel bar with a cooling fluid, or to provide a concentric ller interiorly of the hollow mandrel bar and v:Iill the space therebetween with cooling uid. This has been more or less satisfactory for the smaller diameter work-pieces; but in the larger sizes of expanding mills wherein'pipes are. ex- 3o panded to 2.4 inches and larger sizes, the large volume of uid required to fill the mandrel bars (which have an overall length that in some instances exceeds-70 feet) makes the duid-filled mandrel bar excessively heavy. This excessive heaviness necessitates frequent replacement of the thrust bearing which supports the mandrel bar, causes the rotating mandrel bar to whip and requires excessive power to reciprocate the mandrel bar in order to remove the processed 40 work-piece.

In order to cut down the weight of such a mandrei bar, and at the same time provide an effective cooling means, I-have conceived the spraycooling lof its interior, thereby lightening it to the-extent of as much' as 15,000 pounds, or more than per cent of the usual weight in the larger sizes above mentioned. As can be readily seen, a considerable portion of the strain is thereby ,removed from the supporting thrust bearing 50' which is 'necessarily positioned at4 the extreme rearward end ofthe mandrel bar; there will be less tendency toward whipping; and less power required to reciprocate the mandrel bar.

The foregoing and further objects will be apparent after referring to the drawing, in which:

Figure 1 is a plan illustrating fragmentarily the metal working rolls of a pipe or tube mill, together with the mandrel bar of the present invention. y

' Fig. 2 is anenlarged longitudinal section of 5 I the mandrel bar of Figure 1. l

Referring more particularly to the drawing, the letter A designates a. pair of conventional rotary metal-working rolls which expand the workpiece B by rolling it over a mandrel plug C held 10 in the proper position by the mandrel bar 2 of my invention, the latter being supported by the usual thrust bearing D.-

'I'he mandrel bar 2 is provided with, a bar-cap 3 of suitable conventional shape to hold the man- 15 drel plug C.v The bar-cap 3 is provided with an extending point 4 and a shoulder 5'which has a wear-resistant collar 6 welded or otherwise secured thereto, 'I'he extending point I of the .barcap. 3 has a central bore I which extends com- 20 pletely therethrough. 'I'he extremity of the extending point 4'on the bar-cap 3 is provided with a nozzle tip having vents, or nozzles, 8 through which compressed air is delivered to the interior of the work-piece B as it is being processed, in. a 25 manner toV be later described. 'Ihe barcap 3 is secured to the barrel portion I0 of the mandrel bar by screw-threads and/or welding, asat II. The rearward end of the barrel portion I0 of the mandrel bar 2 carries a thrust member I3 which go,

is secured thereto by screw-threads and/or welding, as at I4. This thrust member I3 is provided wltha rearward radial ange I5 of smaller dianoe eter, and is centrally bored, as at I6, to accon1= modate inner and outer concentric pipes I 1 and 35 I8, respectively.

'Ille inner pipe Il extends forwardly through the barrell portion I 0 of the mandrel bar 2 to carry gas under pressure from a suitable source of supply (not shown) to the nozzles 8, and coma0 municates with the central bore 'I of the extend-- ing` point l of the bar-'cap l by means of a connecting pipe I9 which extends through the bl'- cap and is connectedto the pipe Il by a coupling 20.. For the greater portion of its length, the 46 pipe |1115 disposed along the inner wall of the barrel portion I0 of the mandrel bar 2, and is A secured thereto by collars'ZI. These collars II are secured .to the inner wall of the barrel porl tion t0- of the mandrel bar 2 byweld plugs 22 50 which areformedfrom the exterior thereof. The outer pipe lIl is adapted to carrycooling fluid from 'a suitable source (not shown) to the interior of the barrel portion I Ii of the vmandrel bar 2 through a forwardlyextending pipe 13.1/

vwhich is connected thereto, as at 2l.- Thia forwardly extending pipe 23 is provided with a plurality of risers 25 extending inwardly to the axial center of the mandrel barand rearwardly extending nozzles 28 positioned to direct a spray outwardly onto the interior of `the barrel portion il. The pipe 23 lis oppositely disposed to the pipe II in order to balance the weight of the barrel portion Il, and is secured to the inner wall thereof by collars 21 and weld plugs 2l which are formed'from the exterior thereof. The number of risers 2l and sprayrnozzles'l. provided may be varied to adequately spray-the interior of the barrel portion ll in accordance with the sine thereof. It will be noted that the pipe' Il is wclosed, as at :2,50 that au ofthe num delivered thereinto is forced into the pipe Il.'

The cooling uid -delivered to .the interior of the barrel portion Il is drained Atherefrom through apertures I3 adjacent the rearward end thereof. Since the spray nozzles 2O are directed rearwardly towards thelapertures 3l there will be no tendency to buildup a head,of cooling fluid in the barrel portion Il, and thus the weight will be reduced to a minimum.

' -Whil`e I have shown and described one speciiic embodiment of my invention, it will be understoo'd that I do notrwlsh to-be'limited exactly thereto. since various modications may be made without departing from the scope of my inven.

tion, as dened by the following claims.

I 6mm: v l. A mandrel har for pipe or tubemill operations comp'rising a bar-cap, a thrust member.

abarrelsecuredtoanddisposedbetweensaid har-cap and thrmt manner, said barrel having at leastcne aperhire adjacent the rearward did theredfaaidthrust member having a bore, fluid carryingmeansdispedin saidbore and said barrel, a plurality of risers connected to said lations compridng a bar-cap, a thrust member. a

barrelsecmedtoand'disposedbetween said barcap and thrust member, said barrel having at least one aperture adjacent the rearward end thereof, said thrust member having a bore, fluid carryingmeansdisposedinsaid boreand said barrel, andla plurality of rearwardly directed. spray nonies connected to saidviluid carrying means. f

SRYANT Bumeran. 

